Sewing machine work support



Jan. 18, 1938. L. G. BOWMAN I SEWING MACHINE WORK SUPPORT Original Filed Se t 27', '1955 :s Sheets-Sheet 2 Louis G. Bowman Jan. 18, 1938. B A 2,106,080

SEWING MACHINE WORK SUPPORT I Original Filed Sept. 27. 1955 a Sheets-Sheet} Patented Jan. 18, 1938 NITED STATES PATENT OFFICE SEWING MACHINE WO RK SUPPORT Louis G. Bowman, St. Louis, Mo., assignor to Lewis Invisible Stitch Machine Company, St. Louis, Mo., a corporation of Maine 16 Claims.

This invention relates to new and useful improvements in sewing machines generally, although more particularly to the work support of a blind stitch sewing machine.

This application constitutes a division of my co-pending application Serial No. 42,547, filed Sept. 27, 1935, for improvements in Sewing machines.

The principal object of this invention is to pro- I vide a novel depressible work support and yieldable dual spring mounting therefor whereby a relatively strong resistance to depression of the support is offered during normal sewing operations and a relatively weaker resistance to depression of the support is encountered by an operator when inserting a fabric in the machine or when removing the fabric therefrom.

With the above and other objects in view which will more fully appear, the nature of the invention will be more clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying drawings.

In the drawings:

Figure l is a front elevation of a sewing machine embodying my invention,

Figure 2 is a top plan view thereof,

Figure 3 is a partial right hand elevation of the machine, and Figure 4 is a detail vertical sectional view illustrating the dual spring mounting of the work support.

Like reference numerals designate corresponding parts throughout the several figures of the 35. drawings.

My invention is disclosed as being applied. to a blank stitch sewing machine which embodies a main frame having a base 5, a standard 6, and

a laterally extending arm I which terminates in 40va forwardly extending stitching head 8. A main shaft 9 is journaled in the laterally extending arm I and the upper end of the standard. A horizontal presser foot is rigidly attached to the front end of the forwardly extending head 8. An 45-0scillatory needle 24 and a cooperating stitch forming mechanism are supported on the head 8 and are operatively connected to the main shaft 9.

A work support or table II is pivotally supfioported at 42 on a horizontal shaft 43 supported in and extending laterally from the frame standard 6 in parallelism with the main shaft 9. The support II includes an upstanding guard flange portion 44 and a slightly depressed portion 45- aswhich extends laterally from said support beneath the presser foot 20 as shown in Figures 1 and 2.

A lug I26 depends from the work support M and to this lug a latch dog I2I is pivoted as at I23. The dog I21 includes an eccentric lock surface I29 and a release lug extension I39. The lock surface I29 normally rests on the horizontal leg I3I of a bell crank lever pivoted at I32 onthe frame lug I33, the remaining leg I34 of the bell crank extending downwardly and engaging a strong cushion spring I35 seated in a frame socket I36. The contact between the leg I34 and the spring I35 is made by an adjustable abutment screw I3'I.

By reason of the direct contact between the parts I29, I31, I31, I35 downward movement of the work support 4| is strongly resisted by the spring I35 and the tendency of the spring I35 to force the support upwardly is suitably resisted by an adjustable stop screw I38 threaded through the guard wall 44 and abutting a stop I39 secured on the frame standard. By provision of this equipment a downwardly yieldable work support is provided and yet the spring I35 is much too strong to permit undesirable downward movement thereof.

When it is desired to lower the support M to insert or remove the work, the operator should not be subjected to the severe labor and strain necessary to oppose the relatively stronger spring I35 and for this reason I have provided arelatively lighter spring and means whereby the strong spring may be rendered ineffective and the weaker spring brought into play simultaneously with the effort of lowering the support.

It will be observed by reference to Figure 4 that a coil spring I40 connected to the support ll and the dog I21 serves normally to retain the dog in the position illustrated in Figure 4. The relatively weaker spring above referred to is in the nature of a coil spring IIII coiled about the stud I42 projecting from the frame lug I33 and having one end thereof anchored as at I43 to the frame and the other end I 44 engaging under the work support. 4| as shown in Figure 4. A trip lever v I45 is pivoted intermediate its ends as at I46 to a lug depending from the support 4|. One end of the lever projects under the release lug I30 and tothe remaining end a pull chain I4! is secured. By pulling downwardly on the chain I41 the dog I21 will be tripped to the position illustrated in. dotted lines in Figure 4, thus releasing the support 4 I- from the influence of the relatively stronger spring I35 and permitting the operator tolower the support by use of the chain.

l4! resisted only by the relatively weaker spring I4]. Upon release of the chain the spring I40 will return the dog I31 to the position illustrated in full lines in Figure 4, the eccentric surface I29 facilitating the return to normal engagement with the bell crank leg l3l.

The strong spring I35 is essential to the attainment of even needle penetrations because the needle travels in a fixed path and consequently the same depth of the ridge of material must be always presented to the needle. Thus in the formation of anchor stitches it is necessary that the ridge forming element rise to the same high position in relation to the needle, and the work support which carries the element must be substantially rigid when heavy seams are encountered. The resistance to upward movement of the element must not be solid, however, because if the element could not push the material up through the opening in the presser foot something must yield or break. The spring I35 provides the desirable strong yet yieldable resistance.

When the operator desires to insert work, a slight pull on the chain I41 will release the toggle I45, I21. With the parts in this position the light spring MI alone is effective to hold the work support against depression and only a slight force is necessary to be exerted by the operator to depress the work support 4| sulficiently for inserting the work under the presser foot, or removing work therefrom. In this manner the depression of the work support or table 4| may be said tobe opposed by a primary means and a secondary means of varying degree, and that said means may be rendered selectively dominant.

A stop screw I48 is provided to maintain a working contact between the cam surface of the latch dog I21 and the nose of the leg l3l of the bell crank lever.

It will be seen that the lock surface I29 of the latch dog I21 and the leg I 3| of the bell crank lever, constitute a means which includes thrust applying and releasing elements which are changeable in relation from depressive thrust applying position as shown in Fig. 4 by the full lines, to depressive thrust releasing position as shown in Fig. 4 by the dotted lines.

It is of course to be understood that the details of structure and arrangement of parts may be variously changed and modified without departing from the spirit and scope of my invention.

I claim:

1. In a sewing machine, the combination of a depressible work support, means for imposing upon the support a primary degree of resistance to depression, means for imposing upon the support a secondary degree of resistance to depression, and means for rendering said primary and secondary resistance imposing means selectively dominant.

2. In a sewing machine, the combination of a depressible work support, normally effective means including a relatively strong spring for yieldingly retaining the support against depression, means including a relatively weak spring for retaining the support against depression when said normally effective means is rendered ineffective, and means for rendering said normally effective means ineffective.

3. In a sewing machine, the combination of a depressible work support, normally effective means including a relatively strong spring for yieldingly retaining the support against depression, means including a relatively weak spring for retaining the support against depression when said normally effective means is rendered ineffective, and means for first rendering said normally effective means ineffective and for thereafter depressing the support against the tension of the weaker spring.

4. In a sewing machine, the combination of a depressible work support, means including a relatively strong spring for imposing upon the support a primary degree of resistance to depression, means including a relatively weak spring for imposing upon the support a secondary degree of resistance to depression, and means for rendering said primary and secondary resistance imposing means selectively dominant.

5. In a sewing machine, the combination of a frame including a stitching head, a stitch forming means including a reciprocable needle mounted on the head, a depressible work support mounted on the frame and disposed below said head, means for imposing upon the support a primary degree of resistance to depression, means for imposing upon the support a secondary degree of resistance to depression, and means for rendering said primary and secondary resistance imposing means selectively dominant.

6. In a sewing machine, the combination of a frame including a stitching head, a stitch forming means including a reciprocable needle mounted on the head, a depressible work support mounted on the frame and disposed below said head, normally effective means including a relatively strong spring for yieldingly retaining the support against depression, means including a relatively weak spring for retaining the support against depression when said normally effective means is rendered ineffective, and means for first rendering said normally eifective means ineffective and for thereafter depressing the support against the tension of the weaker spring.

7. In a sewing machine, the combination of a frame including a base, a standard, and an overhanging arm; a stitching head carried by the arm; stitch forming means including a reciprocable needle; a depressible Work support pivotally supported on said standard and extended beneath said head; normally effective means including a relatively strong spring for yieldingly retaining the support against depression; means including a relatively weak spring for retaining the support against depression when said normally effective means is rendered ineffective; and means for rendering said normally effective means ineffective.

8. In a sewing machine, the combination of a frame including a base, a standard, and an overhanging arm; a stitching head carried by the arm; stitch forming means including a reciprocable needle; a depressible work support pivotally supported on said standard and extended beneath said head; normally eifective means including a relatively strong spring for yieldingly retaining the support against depression; means including a relatively weak spring for retaining the support against depression when said normally effective means is rendered ineifective; and means for first rendering said normally effective means ineffective and for thereafter depressing the support against the tension of the weaker spring.

9. In a sewing machine, the combination of a depressible work support, means including thrust applying and releasing elements changeable in relation from depressive thrust applying to depressive thrust releasing position for resisting or permitting depression of the support, light spring means for resisting depression of the support when said elements are in thrust releasing position, and means to move said elements.

10. In a sewing machine, the combination of a depressible work support, means including thrust applying and releasing elements changeable in relation from depressive thrust applying to depressive thrust releasing position for resisting or permitting depression of the support, light spring means for resisting depression of the support when said elements are in thrust releasing position, and means for changing the relation of said elements to negate their resisting function and to depress the support against the tension of said spring to change their relation.

11. In a sewing machine, a frame, a depressible support mounted on the frame, a relatively strong spring, make and break thrust connections interposed between the strong spring and the support to normally offer strong yieldable resistance to depression of said support, means to break the connections and the strong resistance to depression of the support, and a weak spring effective to resist depression of the support when said connections are broken.

12. In a sewing machine, a frame, a depressible support mounted on the frame, a relatively strong spring, a thrust lever pivoted to the frame and engaging the strong spring, a thrust link pivotally supported on the support and movable into and out of engagement with the lever to respectively impart depressive thrusts to the lever and the strong spring or to relieve the support of the resistance of said strong spring, and a weak spring effective to resist depression of the support when the link and lever are disengaged.

13. In a sewing machine, a frame, a depressible support mounted on the frame, a relatively strong spring, a thrust lever pivoted to the frame and engaging the strong spring, a thrust link pivotally supported on the support and movable into and out of engagement with the lever to respectively impart depressive thrusts. to the lever and the strong spring or to relieve the support of the resistance of said strong spring, a weak spring effective to resist depression of the support when the link and lever are disengaged, and means for moving the link out of engagement with the lever and for depressing the support.

14. In a sewing machine, a frame, a depressible support mounted on the frame, a relatively strong spring, a thrust lever pivoted to the frame and engaging the strong spring, a thrust link pivotally supported on the support and movable into and out of engagement with the lever to respectively impart depressive thrusts to the lever and the strong spring or to relieve the support of the resistance of said strong spring, a weak spring effective to resist depression of the support when the link and lever are disengaged, means for moving the link out of engagement with the lever and for depressing the support, and means to automatically restore link and lever engagement when the depressing force on the support is released.

15. In a sewing machine, the combination of a depressible work support, means for imposing upon the support a primary degree of resistance to depression, means for imposing upon the support a secondary degree of resistance to depression, means for rendering said primary and secondary resistance imposing means selectively dominant, and adjustable means cooperating with said primary resistance imposing means for adjusting the extreme upward limit of movement of the work support.

16. In a sewing machine, a frame, a depressible support mounted on the frame, a relatively strong spring, a thrust lever pivoted to the frame and engaging the strong spring, a thrust link pivotally supported on the support and movable into and out of engagement with the lever to respectively impart depressive thrusts to the lever and the strong spring or to relieve the support of the resistance of said strong spring, a weak spring effective to resist depression of the support when the link and lever are disengaged, means for moving the link out of engagement with the lever and for depressing the support, and means for limiting freedom of movement of the lever during disengagement of said lever and link.

LOUIS G. BOWMAN. 

